Veterinary Services

 
Copper poisoning was confirmed on an Aberdeenshire unit in a group of crossbred gimmers grazing land on which distillery sludge had been applied.  The sheep were immediately removed from this area and action was taken to prevent affected animals from entering the food chain.

Parasitic diseases

Establishing a diagnosis of coccidiosis in the live lamb can be problematic, since it relies not only on demonstrating a high faecal oocyst counts, but also on the identification of a significant proportion of pathogenic Eimeria species.  At necropsy the use of histopathology on the affected areas of intestine may also assist in reaching a diagnosis, as it did in the case of a three-week-old lamb submitted to Edinburgh.  The history was of diarrhoea within a group of Suffolk-cross lambs over the previous four days, during which 15 animals had died.  In this case the bowel was grossly normal and no oocysts were detected within the gut contents.  However histology revealed large numbers of immature and mature coccidial forms and associated damage to the mucosa of the small and large intestine.

Coccidiosis was diagnosed in another four-week-old crossbred lamb at grass, the third lamb reportedly affected by diarrhoea.  Postmortem examination revealed enteritis affecting the distal small and large intestine with thickening and gross enlargement of mesenteric lymph nodes.  In this case large numbers of coccidial oocysts were demonstrated on scrapes from the affected areas of gut and histopathology revealed infiltration of the affected mucosa by immature and mature coccidia.

Generalised and systemic conditions

Increased neonatal mortality was investigated in a Sutherland sheep flock. Approximately 30 lambs from one to four weeks of age were found dead at pasture. Necropsies confirmed variously Mannheimia haemolytica septicaemia and pneumonia and Escherichia coli septicaemia.  A subsequent farm visit identified the overuse of supplementary minerals for the lambing flock, and in particular an excessive supply of iodine.  A connection has previously been made between high levels of iodine fed to ewes in late pregnancy and a reduced ability to absorb colostral immunoglobulin, leaving lambs vulnerable to neonatal infection.  Further monitoring of this case is on-going.

Alimentary tract disorders

A one-year-old Dorset cross gimmer was submitted with a history of weakness and mild ataxia.  This condition progressed overnight to anorexia, tachycardia and hypothermia, after which the animal was euthanased.  At necropsy the gimmer was found to be in exceptionally good condition, with substantial fat reserves.  There was some 15 litres of clear orange-coloured fluid within the abdomen, from which Candida albicans was isolated in profuse and pure growth.  No evidence of trauma was found on further examination of the carcase.  Histopathological changes noted in portions of the omentum were consistent with partially necrotic adipose tissue, infiltrated by large numbers of Candida yeasts and pseudohyphae. SAC C VS speculated on an underlying fat necrosis in this case, although there was no clear explanation of how the yeast infection was initiated.

Reproductive tract conditions

A three-year-old Texel cross ewe lambed unassisted and was seen in the morning on its feet, with live twin lambs.  However by midday the ewe had collapsed and was submitted alive to Dumfries for necropsy.  Clinical examination confirmed tachypnoea and tachycardia.  The mucous membranes were brick red and a pyrexia of over 42° C was recorded before the animal was euthanased.  Necropsy revealed a pleural effusion containing a fibrin clot and an increased volume of pericardial fluid.  The liver was pale.  The ewe had cleansed, however the uterus smelled putrid and the endometrium was dark red in colour.  A fluorescent antibody test (FAT) and anaerobic culture of the endometrium confirmed the presence of Clostridium sordellii.   Histopathology identified a severe haemorrhagic metritis with marked oedema and rod-shaped bacteria embedded in the mucosa.   Clostridium sordellii metritis was diagnosed.

Foetuses were received from a flock experiencing abortions amongst gimmers on one particular area of hill for the second successive year.  Bloods from affected gimmers were sero-positive to tick borne fever agent and it was suggested that this was the underlying problem.  Interestingly, the farm in question had a history of tick borne fever causing foetal losses within the suckler cow herd.

Triplet lambs and placentae were received at Edinburgh from a farm with a history of multiple abortions due to E. coli infection in 2009.  The foetuses were partly mummified but E.coli was isolated in pure growth from a swab of the stomach lining.  Further typing of this isolate confirmed it to be of a potentially pathogenic strain.
 
A review of abortion diagnoses recorded by SAC C VS in 2010 will appear in the May monthly report.

Musculo-Skeletal conditions

Seven outbreaks of infectious polyarthritis of lambs due to Streptococcus dysgalactiae subsp. dysgalacticae were diagnosed. Two lambs were submitted to Dumfries from a flock where a total of 30 lambs of less than three weeks of age were reported to be affected.  Cloudy joint fluid or frank pus was found in all the limb joints in both cases and in one lamb the organism was also isolated from endocarditis lesions on the right atrio-ventricular valve.  In one outbreak in the Aberdeen area clinical diagnosis was more difficult since the infection was restricted to the atlanto-occiptal joint and lambs presented in lateral recumbency.

Nervous system disorders

Louping-ill was diagnosed as the cause of acute death following neuropathological examination of the brains of two hoggs.  These animals were submitted for postmortem examination from an Argyllshire island flock where five hoggs died over a period of five days.  The same diagnosis was made following neuropathology on the brain of a Scottish mule hogg.  Five of a group of 50 hoggs, also in Argyllshire, died after showing hyperaesthesia and a high-stepping gait. Neither farm had treated with an acaricide nor vaccinated against louping-ill.

Renal diseases

A six-week-old Texel cross lamb was submitted to Perth with a history of death following a period of anorexia and depression, despite treatment with antibiotics.  Another individual in the same field had been seen standing for long periods with its head over the water trough, an unusual finding in suckled lambs.  Postmortem examination revealed greatly enlarged kidneys that were pale and soft in consistency confirming a diagnosis of nephrosis.